A conventional agricultural combine includes a header assembly for severing and collecting crop materials as the combine is driven through a field and a feeder mechanism for advancing and elevating the crop materials to a threshing area on the combine. In the threshing area of the combine, the crop material is threshed as it passes between a rotor assembly and a stationary generally cylindrical housing.
A typical rotor assembly includes an elongated rotor including a series of metallic thresher elements peripherally arranged thereabout. An outer surface on the thresher elements is arranged proximate to the cylindrical housing. The rotor is mounted on a frame of the combine and is rotatably driven at variable speeds depending on the crop material being harvested. Conventional thresher elements have a rasp or tooth-like configuration on the outer surface which impacts with crop materials as the rotor assembly is driven.
The impact of the crop materials against any of the multitude of edges on the rasp or tooth-like outer surface on the thresher elements naturally tends to cause damage to the crop materials. That is, the impact of the slower moving crop materials against and coupled with the relative movement between the threshing element edges and the crop material naturally results in some level of abrasive action which typically damages the crop material. As used herein, the term "damage" is meant to include splitting, cracking, nicking, scratching, and/or marring of the harvested crop materials.
As will be appreciated, damaged crop material is an inferior grade of product which quickly spoils and, therefore, only a relatively small percentage (typically 7-10%) is permitted by volume in those products intended for human consumption. Because only a relatively small percentage of damaged material is permitted in those products intended for human consumption such as corn, soybeans, kidney beans, peas and others, farmers are paid a premium price for crop materials having a relatively low damage content by volume at a collection station.
Reducing the operational speed of the rotor assembly has been proposed to limit crop material damage by the thresher elements of the combine. As will be appreciated, reducing the speed of the rotor assembly likewise reduces the overall capacity of the combine and, thus, detracts from productivity and, therefore, the profits the farmer may realize for the harvested crop material will be effected.
Another proposal to reduce damage to crop materials involves facing or plating the rasp-like configured threshing elements with chrome or other forms of metal. During combine operation, the threshing elements are subjected to considerable abrasive action by reason of dust and gritty materials brought into the threshing area from the field. Due to the speed of the rotor which must be maintained for efficient threshing, coupled with the abrasive material, rapid wear of the facing or plating on the threshing elements typically occurs. Unless new threshing elements are held in inventory, considerable down time of the combine is incurred. Adding new thresher elements to the rotor assembly is also expensive. Moreover, the damage to the grain is not readily perceivable by the farmer and, thus, he will not be able to tell if new parts are required until the harvested grain is graded at the collection point.
Thus, there remains a need and a desire for threshing elements which are designed to inhibit damage to crop materials impacting with and moving past the threshing elements thereby enhancing combine performance.